刚体模拟一向是计算机图形学中的重要课题，其重要性体现在包括军事仿真、影视制作和电子游戏在内的多个领域中。刚体破碎模拟广泛地出现在电子游戏的各类应用场景中：一方面，破碎场景与动作、射击和解谜等玩法联系得非常紧密，可以提升游戏性；另一方面，游戏物件与玩家之间的交互可以提高游玩过程中的沉浸感。考虑到当前业界精品化的开发趋势以及移动端市场扩大的情景，无论是从游戏性角度还是从交互角度，目前游戏对破碎模拟的要求都在提高。当前游戏中的破碎模拟方案普遍存在以下方面的问题：性能要求高、衍生设计复杂、多平台支持不充分。基于实际的业界需求，本文提出了一种新的刚体破碎模拟方法。首先，基于沃洛诺伊划分方法，对三角网格进行空间划分。其次，以代表材料特性的二维纹理样例作为输入，基于最优化方法，生成空间标量场描述刚体的内部特性。最终，将标量场映射至碎块连接键，与网格体相结合，对破碎物体对象进行实时物理模拟。相比业界现有的常见方法，本方法的优势在于：资产创建效率高、表现细节更丰富，以及运行时性能的提升。本文的主要工作和贡献如下：（1）将基于几何的方法与基于物理的方法进行了结合，达成了性能与表现力的平衡。在预切分阶段选择了基于几何的方法，采用以德劳内三角化为核心的沃洛诺伊切分，对三角网格对象进行划分。此外，通过基于最优化的方法以纹理样例作为输入，构建了表达刚体内部特征的空间标量场，用以增加模拟时的细节，为管线中的白盒控制提供支持。（2）基于空间标量场对碎块对象进行组合焊接，有效地提升了运行效率。通过将标量场映射至碎块连接键的形式，有效地减少了物理对象的数量，减少了运行时消耗在物理线程中的时间。（3）建立了完整的适用于工业管线的破碎框架，提高开发效率。搭建了多层次的框架并提供了丰富的方法，直接调用了底层库用于高效运行并调试，也在虚幻引擎中被应用于管线化的工业设计。既完成了运行时实时物理模拟，也完成了基于物理的动画的生成用于离线渲染。既应用于主机和 PC 客户端，也适用于移动客户端。
Rigid body simulation has always been a hot topic in computer graphics. Its importance lies in military industry, film industry and video game industry. There are two main reasons why rigid body destruction simulation takes place frequently in recent video games. On one hand, destruction scenes are heavily related with game-play mechanics， including ACT, shooting and puzzle. On the other hand, interaction between players and game objects in virtual scenes will increase the sense of immersion of players.Main challenges of destruction simulation in video games are: (1) High performance requirements. (2) Complexity in related designs. (3) Insufficiency in support for multi-platform. Based on need in real development, a new rigid body destruction simulation method has been implemented in this thesis. First, a triangular mesh object is fractured with Voronoi Diagram based methods. Second, a 2-dimensional texture exemplar is taken as input, which represents the inner feature of a material, in order to generate 3-dimensional scalar field based on an iteratively searching and optimizing approach. Finally, the scalar field is combined with the mesh assets, to finish real-time physics simulation in virtual scenes.Compared with existing methods, the advantages of this method lie in efficiency in digital asset creation, richness of simulation details and improvement in run-time performance.In general the contribution and creativity of this thesis lie in three ways:(1) Combination of geometry-based methods and physics-based methods, achieving a balance between performance and fidelity. Geometry-based methods are chosen in the pre-fracture phase, as Voronoi Diagram based on Delaunay Tetrahedralization is used to cut the triangular mesh. Besides, 2-d texture exemplar taken as input, Optimization-based approach is used to generate spatial scalar field, increasing simulation detail as well as supporting white-box control.(2) Increase in run-time efficiency with welding of objects based on spatial scalar field.As the spatial scalar field is mapped to connection bonds between chunks, the number of physics objects are reduced effectively, reducing the time spent in physics thread.(3) A complete framework for pipelined industry is built, increasing development efficiency. Direct call of low-layer APIs and pipelined application inside Unreal Engine are both allowed. Real-time physics simulation and off-line physics-based animation generation are both implemented. Game clients on Console, on PC and on mobile devices are all supported.
